Enhanced recoverable energy density in Ca0.7Sm0.2TiO3-modified Bi0.5Na0.5TiO3–SrTiO3 ceramic capacitors

Ceramic capacitors are receiving increasing interest because of their applications in pulsed-power devices. The perovskite oxide Bi 0.5 Na 0.5 TiO 3 (BNT)-based ferroelectric ceramics are regarded as prospective lead-free candidate for dielectric capacitors because of the high polarization and outstanding relaxor behaviour. Herein, the relaxor ferroelectric (0.7− x )Bi 0.5 Na 0.5 TiO 3 –0.3SrTiO 3 – x Ca 0.7 Sm 0.2 TiO 3 ceramics synthesized through solid-state route and exhibited pseudocubic perovskite structure and strong relaxor behaviour. With increasing Ca 0.7 Sm 0.2 TiO 3 content, the moderate permittivity and reduced grain size contributed to the monotonically increased electric breakdown strength. Among prepared samples, the x = 0.2 ceramic displayed slimmer polarization-electric field curves with a remarkable recoverable energy density (~6.8 J/cm 3 ) and a satisfied efficiency (~82.2%) under external electric field of 450 kV/cm. Moreover, the x = 0.2 ceramic also exhibited a superb thermal reliability of energy storage properties (3.9–4.5 J/cm 3 with variation of 13.3% in 25–160 °C) resulting from the diffuse phase transition. The above results make the x = 0.2 ceramics becoming promising candidates for pulsed-power devices.